Picked up by the ever-alert Patently Apple, Apple has quietly filed a patent detailing the return of Touch ID and how it would work alongside Face ID in new iPhones. What’s more, this is Touch ID unlike anything iPhone users have experienced before.

Apple iPhone XI concept

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Taking inspiration from rivals, Apple shows-off work to build Touch ID into the display of iPhones. For example, Apple’s patent demonstrates it operating as a backup to Face ID for unlocking iPhones but it can also operate as a standalone authentication method itself.

“[T]oday's report does in fact show interfaces confirming that dual biometrics could be coming to future iPhones”, confirms Patently Apple and the news also means that where there was once smoke, it is beginning to look a lot like fire.

Why? Because this is Apple’s second leak detailing an in-display Touch ID iPhone in a month. Earlier in December, Apple also filed new iPhone Touch ID patents devised by engineer Dale Setlak, who joined from Authentec, the company Apple bought in 2012 to acquire the technology behind Touch ID.

Interestingly, one quirk of the latest patents is Apple illustrates them using an iPhone 6-style phone, but don’t be fooled. The company often uses older models as it’s a simple way to avoid revealing future designs. And here’s the kicker: the patents show Apple initially filed them privately almost a year ago, so this tech is well down the road.

But why would the return of Touch ID be so useful? In short: convenience and security.

First, there are undoubtedly times when unlocking a phone with a fingerprint is more convenient than holding it up to your face. Second, the real strength of biometric security is not in isolation but combination. Simultaneous verification with both fingerprint and face is extremely strong and with Apple already revealing plans to promote iPhones are potential passport and ID document replacements, such an upgrade would be essential.

Needless to say, until Tim Cook is holding up such an iPhone on stage things can change. But right now combining the industry’s best facial recognition with a (presumably ultrasonic-based) in-display Touch ID display is a win-win.